[R] Detection Times and Poisson Distribution

[Lorenzo Isella]

Dear All,
Apologies if my questions are too basic for this list.
I am given a set of data corresponding to list of detection times (real, 
non-integer numbers in general) for some events, let us say nuclear 
decays to fix the ideas.
It is a small dataset, corresponding to about 400 nuclear decay times.
I would like to test the hypothesis that these decay times are 
Poissonian-distributed.
What is the best day of dealing with the data? Should I consider the 
cumulative number of detections vs time, the time intervals between two 
consecutive detections vs time or something else?
Many thanks

Lorenzo